vulnerability

Amazon Linux AMI 2: CVE-2022-49708: Security patch for kernel (Multiple Advisories)

Severity
6
CVSS
(AV:L/AC:L/Au:S/C:C/I:N/A:C)
Published
2025-02-26
Added
2025-03-14
Modified
2025-03-17

Description

In the Linux kernel, the following vulnerability has been resolved:

ext4: fix bug_on ext4_mb_use_inode_pa

Hulk Robot reported a BUG_ON:
==================================================================
kernel BUG at fs/ext4/mballoc.c:3211!
[...]
RIP: 0010:ext4_mb_mark_diskspace_used.cold+0x85/0x136f
[...]
Call Trace:
ext4_mb_new_blocks+0x9df/0x5d30
ext4_ext_map_blocks+0x1803/0x4d80
ext4_map_blocks+0x3a4/0x1a10
ext4_writepages+0x126d/0x2c30
do_writepages+0x7f/0x1b0
__filemap_fdatawrite_range+0x285/0x3b0
file_write_and_wait_range+0xb1/0x140
ext4_sync_file+0x1aa/0xca0
vfs_fsync_range+0xfb/0x260
do_fsync+0x48/0xa0
[...]
==================================================================

Above issue may happen as follows:
-------------------------------------
do_fsync
vfs_fsync_range
ext4_sync_file
file_write_and_wait_range
__filemap_fdatawrite_range
do_writepages
ext4_writepages
mpage_map_and_submit_extent
mpage_map_one_extent
ext4_map_blocks
ext4_mb_new_blocks
ext4_mb_normalize_request
>>> start + size ac_o_ex.fe_logical
ext4_mb_regular_allocator
ext4_mb_simple_scan_group
ext4_mb_use_best_found
ext4_mb_new_preallocation
ext4_mb_new_inode_pa
ext4_mb_use_inode_pa
>>> set ac->ac_b_ex.fe_len
ext4_mb_mark_diskspace_used
>>> BUG_ON(ac->ac_b_ex.fe_len

we can easily reproduce this problem with the following commands:
`fallocate -l100M disk`
`mkfs.ext4 -b 1024 -g 256 disk`
`mount disk /mnt`
`fsstress -d /mnt -l 0 -n 1000 -p 1`

The size must be smaller than or equal to EXT4_BLOCKS_PER_GROUP.
Therefore, "start + size ac_o_ex.fe_logical" may occur
when the size is truncated. So start should be the start position of
the group where ac_o_ex.fe_logical is located after alignment.
In addition, when the value of fe_logical or EXT4_BLOCKS_PER_GROUP
is very large, the value calculated by start_off is more accurate.

Solution(s)

amazon-linux-ami-2-upgrade-bpftoolamazon-linux-ami-2-upgrade-bpftool-debuginfoamazon-linux-ami-2-upgrade-kernelamazon-linux-ami-2-upgrade-kernel-debuginfoamazon-linux-ami-2-upgrade-kernel-debuginfo-common-aarch64amazon-linux-ami-2-upgrade-kernel-debuginfo-common-x86_64amazon-linux-ami-2-upgrade-kernel-develamazon-linux-ami-2-upgrade-kernel-headersamazon-linux-ami-2-upgrade-kernel-livepatch-4-14-285-215-501amazon-linux-ami-2-upgrade-kernel-livepatch-5-10-126-117-518amazon-linux-ami-2-upgrade-kernel-livepatch-5-15-50-23-125amazon-linux-ami-2-upgrade-kernel-toolsamazon-linux-ami-2-upgrade-kernel-tools-debuginfoamazon-linux-ami-2-upgrade-kernel-tools-develamazon-linux-ami-2-upgrade-perfamazon-linux-ami-2-upgrade-perf-debuginfoamazon-linux-ami-2-upgrade-python-perfamazon-linux-ami-2-upgrade-python-perf-debuginfo
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